@estherara,
Hi- you are exactly correct.
'Potential' energy is energy stored, ready to be released. If an object has already been dropped, it has fallen and has released its potential energy - it no longer has any potential. Therefore your sentence should read...
"A 'dropped object' is any item (or object) that HAS FALLEN from any height."
If you want to convey 'the potential to fall'...
'A 'SUSPENDED OBJECT" is any item (or object) that has the potential to fall from any height to a lower elevation.'
Although the cleanest opposite of 'drop' is 'rise'. So you could also say 'A RISEN object is any item that has the potential to fall from any height....
Finally- don't forget "Drop" and "Rise" don't only mean something physical falling from one elevation to another. Scientific readings, musical pitch, wind speed, and many other things can drop and rise.... you can also 'drop' (remove from your schedule) a college course. Good old English ;-)